This invention is related to braking apparatus, methods, and related systems for large vehicles, such as locomotives. In particular, the invention is directed to electronically controlled parking brake systems that provide a reliable and systematic process for braking such vehicles.
Locomotives use parking brakes to ensure that they remain parked, and do not move accidentally when left unattended. In the past, such brakes have been manually set by repeated and forceful pulls upon a lever or handle located on the locomotive. Such prior art braking apparatus have been manually set by a hand-actuated ratchet lever that tensions a brake chain connected to a wheel brake. The wheel brake typically is set when the brake chain applies sufficient tension to the wheel brake. Setting a brake manually is a labor intensive process which requires significant strength and agility to perform properly.
Because of the large amount of force typically required to manually set such brakes, physical injuries or strains may occur when personnel use such manual parking brake systems. Also, train employees must have significant body strength to operate such parking brake systems. If an employee is not strong enough, or has a physical disability, it is generally more difficult for him or her to accomplish the setting of a brake. Further, if an employee is injured in the course of employment, it could be very difficult or impossible for that employee to activate the emergency parking brake system. Further, many small men and women find it impossible to generate enough force to set a brake manually. Without sufficient force applied to the parking brake the locomotive can begin to roll and move out of control down the track. Runaway conditions such as described herein have in the past resulted in serious injury and property damage.
It is advantageous to make it more convenient for an employee to set a train brake. The easier it is to actually set such a brake, the more likely it will be that the brake will be set routinely and properly, thereby reducing the likelihood of accidents. Developments that can save manual steps in the setting or releasing of train brakes are needed to promote the use of such safety parking brake systems at all times, thereby reducing the rate of accidents. Automating the process allows for a more consistent force to be applied each time the brake is operated.
Power assisted train brakes have been used in some applications. For example, U.S. Pat. No. 6,039,158 (the ""158 patent) describes a power assisted locomotive parking brake. The brake uses a motor and planetary reduction drive. The system also provides a manual drive that is located between the powered drive and the actuating mechanism. In order to draw up (i.e. set) the brake chain, as described in the ""158 patent, the ratchet handle is pulled repeatedly. Further, in order to release the brake, a release handle is pulled to release a ratchet mechanism, thereby facilitating release of the brake.
In determining that a locomotive parking brake is actually set, prior art systems sometimes rely upon visual observations. In other systems, a device has been employed that senses the brake chain position and provides this information to the cab of the locomotive. However, these prior methods of detecting that a brake in fact has been applied in a locomotive are not always reliable. When relying upon visual observation, human error may occur. Further, systems that rely upon the position or take-up length of the brake chain fail to account for situations in which foreign material or debris in the brake chain area improperly causes a false indication that the chain has been applied, when in fact the chain may have malfunctioned. Thus, the chain position may deceive the operator into believing that a proper braking force has been applied to the locomotive wheel, when in fact the correct amount of force has not been applied to the wheel. A system that is capable of more reliably determining when a parking brake has been set by measuring the braking force applied to the wheel, would be highly desirable.
The invention provides a power driven brake system for a locomotive capable of applying force via the locomotive brake chain to stop rotation of a locomotive wheel and thereby set the parking brake. The actuating mechanism is capable of operating in a first mode to set the brake and in a second mode to release the brake. The mechanism further comprises a motor, a clutch connected to the motor, a gearing mechanism, a ratchet mechanism and a dual acting solenoid connected to the ratchet mechanism. The dual acting solenoid may actually comprise separate solenoid mechanisms, each operating in opposite directions. In other embodiments, the dual acting solenoids may work in tandem. At the output of the gearing mechanism is a sprocket which connects to the locomotive brake chain. The motor, clutch and solenoid are controlled by an electronic control system thereby facilitating the setting and releasing in succession without manual reconfiguration of the actuating mechanism or gearing mechanism.
The apparatus comprises both a manual and an automatic actuatingmechanism, such that both the manual and automatic systems are capable of setting, locking and releasing the brake. The manual actuating mechanism comprises a plurality of gears that are capable of reducing the load required to set the brake such that the amount of force needed to set the brake when operating the lever manually is minimized. In some applications, the force is no more than about 75 lbs. of force.
In other aspects of the invention, a control interface is provided that is capable of sending signals to the actuating mechanism to facilitate locking or releasing the brake remotely, that is, from a location away from the actuating mechanism. The remote control interface may be located on the locomotive, for example in the locomotive cab, or it may be located away from the locomotive, employing a wireless communications device to communicate with the electronics of the actuating mechanism.
Load sensing apparatus is typically provided, with the apparatus being capable of detecting the amount of force applied to the locomotive wheel. The load sensing apparatus transmits an electrical signal to the actuating mechanism indicating to the motor that it should turn off upon reaching a predetermined load threshold, stopping rotation of the chain sprocket. The load sensor may operate by (1) measuring the load applied upon the motor, and (2) in another embodiment may operate by sensing the load applied at the brake itself (which is a more direct measurement of braking force). The electronic control system, when operating in the automatic mode, is capable of reliably indicating when the predetermined force level has been reached.
In another aspect of the invention, a signal is sent back to the locomotive cab as a reliable indication of whether or not the brake is adequately set.